Processes and incremental transducers as well as measured material elements for incremental transducers for determining actual positions of a body along a measuring path and/or the change therein are generally known. They are frequently used, for example, to monitor and control mechanical motion processes. For example, DE 196 21 015 C2 shows a device for detecting the position of moving machine parts, whose measured material element is composed of a plurality of timing lineals. Furthermore, incremental transducers are used to detect the rpm (speed) of and to control motors.
Incremental transducers differ from absolute value transducers in that they make available actual positions or changes in the actual position of a body only relative to an initial position at a starting intersection. The distance from the initial position is often determined on the basis of a number of position markers arranged between the initial position and the actual position. Absolute value transducers can determine the position, as the name implies, in absolute terms, i.e., not only relative to a starting position. The absolute position is preferably coded directly in the position code of the measured material element.
Prior-art measured material elements are not practical especially for the determination of the actual position and/or of the change in the actual position of large bodies, for example, a shaft of a wind power plant. Measured material elements have hitherto been adapted to the dimensions of the body to be monitored and often mounted in a closed form at the body. Consequently, the prior-art measured material elements are at times very large and can be manufactured and mounted at a high cost only.
Pre-assembled measured material elements cannot frequently be used, because dimensional imperfections of the body cannot be readily compensated with such a measured material element. For example, the diameter of the shaft of the wind power plant may deviate by up to 1 mm or more from a desired value. A measured material element manufactured in respect to the desired value can be mounted on such a shaft with difficulty only if at all.
Measured material elements are also difficult to manufacture for irregular measuring paths. To establish, for example, motions of the body along a measuring path that is composed of translatory and/or rotator motions, a corresponding measured material element, which is possibly of an irregular shape, must be manufactured. However, the manufacture of such a measured material element is very susceptible to dimensional tolerances.
If measured material elements are adapted to bodies having greater dimensional tolerances, while the actual location frequency of the position markers remains unchanged, the measuring resolution expected by a downstream electronic system may not possibly be offered by the incremental transducer having the assembled measured material element. Furthermore, such an incremental transducer cannot deal with changes in the dimensions of the body that occur during the lifecycle of the incremental transducer.